Electrically assisted attachment of medical devices to thrombus

ABSTRACT

A medical device configured to perform an endovascular therapy can include an elongate manipulation member and an intervention member. The elongate manipulation member can include a distal end portion. The intervention member can include a proximal end portion and a mesh. The proximal end portion can be coupled with the distal end portion of the elongate manipulation member. The mesh can have a plurality of cells in a tubular configuration and being compressible to a collapsed configuration for delivery to an endovascular treatment site through a catheter and being self-expandable from the collapsed configuration to an expanded configuration. The mesh can include an anodic metal and a cathodic metal. The anodic metal and the cathodic metal can each form a fraction of a total surface area of the mesh.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/605,169, filed May 25, 2017, which is a continuation of U.S. patentapplication Ser. No. 14/541,094, filed Nov. 13, 2014, now issued as U.S.Pat. No. 9,795,400, which claims the benefit of U.S. Provisional PatentApplication No. 61/903,518, filed Nov. 13, 2013, the disclosures ofwhich are incorporated herein by reference in their entireties.

BACKGROUND

Blood vessels can become partially or completely occluded by emboli,e.g., thrombi, thereby impeding or disrupting the flow of bloodtherethrough. For example, intracranial arteries can become occluded bythromboembolisms. Disruption of blood flow by the occlusion can preventoxygen and nutrients from being delivered to tissues downstream of theocclusion. Deprivation of oxygen and nutrients to tissue distal to anocclusion can impair proper function of the tissue, and may result incellular death. Cellular death increases with duration of the occlusion.

SUMMARY

An aspect of at least some of the embodiments disclosed herein involvesthe recognition that a galvanically induced electrical charge can assistattachment of preexisting thrombotic material to a mechanicalthrombus-retrieval device and, thereby, improve a likelihood ofsuccessful thrombus capture and retrieval from a patient's body. Theelectrical charge generated by a galvanic couple can cause or increaseadhesion between one or more of the metals in the galvanic couple andthe thrombotic material.

The subject technology is illustrated, for example, according to variousaspects described below. Various examples of aspects of the subjecttechnology are described as numbered clauses (1, 2, 3, etc.) forconvenience. These are provided as examples and do not limit the subjecttechnology. It is noted that any of the dependent clauses may becombined in any combination, and placed into a respective independentclause, e.g., clause 1, 17, or 20. The other clauses can be presented ina similar manner.

1. A medical device configured to perform an endovascular therapy, thedevice comprising:

-   -   an elongate manipulation member comprising a distal end portion;        and    -   an intervention member comprising a proximal end portion and a        mesh, the proximal end portion being coupled with the distal end        portion of the elongate manipulation member, the mesh having a        plurality of cells in a tubular configuration and being        compressible to a collapsed configuration for delivery to an        endovascular treatment site through a catheter and being        self-expandable from the collapsed configuration to an expanded        configuration, and the mesh comprising an anodic metal and a        cathodic metal, and the anodic metal and the cathodic metal each        forming a fraction of a total surface area of the mesh.

2. The medical device of Clause 1, wherein the fraction of the surfacearea formed by the anodic metal is located primarily at an internalaspect of the mesh.

3. The medical device of Clause 1, wherein less than 50% of the surfacearea formed by the anodic metal is located at an external surface of themesh.

4. The medical device of Clause 1, wherein 35% to 85% of the surfacearea of the mesh is formed by the anodic metal.

5. The medical device of Clause 1, wherein an outwardly facing surfaceof the mesh is formed substantially only by the cathodic metal.

6. The medical device of Clause 1, wherein the fraction of the surfacearea formed by the anodic metal comprises a plurality of discreteportions of the anodic metal.

7. The medical device of Clause 1, wherein the fraction of the surfacearea formed by the anodic metal is contiguous.

8. The medical device of Clause 1, wherein an engagement portion of thesurface area is configured to engage an interior surface of a catheterduring delivery of the medical device through a lumen of the catheter,and an average coefficient of friction of the engagement portion is lessthan an average coefficient of friction of the surface area excludingthe engagement portion.

9. The medical device of Clause 1, wherein an engagement portion of thesurface area is configured to engage an interior surface of a catheterduring delivery of the medical device through a lumen of the catheter,and substantially none of the engagement portion is formed by the anodicmetal.

10. The medical device of Clause 1, wherein the anodic metal is indirect contact with the cathodic metal.

11. The medical device of Clause 1, wherein at least a portion of theanodic metal has a thickness of at least 2 μm.

12. The medical device of Clause 1, wherein the anodic metal comprisesmagnesium and the cathodic metal comprises nickel and titanium.

13. The medical device of Clause 1, wherein the mesh is rolled in thecollapsed configuration such that a first portion and a second portionof the mesh are overlapped in at least one radial direction with asurface area of the first portion contacting a surface area of thesecond portion, and each of the surface area of the first portion andthe surface area of the second portion comprises substantially no anodicmetal.

14. The medical device of Clause 1, further comprising a temporary covermaterial that encapsulates at least a portion of the anodic metal.

15. The medical device of Clause 14, wherein the temporary covermaterial is erodible, dissolvable, degradable or absorbable in vivo.

16. The medical device of Clause 15, wherein the temporary covermaterial encapsulates substantially all of the anodic metal.

17. A medical device configured to perform an endovascular therapy, thedevice comprising:

-   -   an elongate manipulation member comprising a distal end portion;        and    -   an intervention member comprising a proximal end portion and a        mesh, the proximal end portion being coupled with the distal end        portion of the elongate manipulation member, the mesh having a        plurality of cells in a tubular configuration and being        compressible to a collapsed configuration for delivery to an        endovascular treatment site through a catheter and being        self-expandable from the collapsed configuration to an expanded        configuration, and the mesh comprising means for galvanically        assisting internal attachment of the mesh to thrombus.

18. The medical device of Clause 17, wherein the means for galvanicallyassisting attachment of the mesh to thrombus comprises an anodic metaland a cathodic metal.

19. The medical device of Clause 17, wherein the anodic metal comprisesmagnesium and the cathodic metal comprises nickel and titanium.

20. A method for performing an endovascular therapy, comprising:

-   -   identifying a blood vessel in which blood flow is impeded by        thrombus;    -   inserting a medical device into the blood vessel, the medical        device comprising:        -   an elongate manipulation member comprising a distal end            portion; and        -   an intervention member comprising a proximal end portion and            a mesh, the proximal end portion being coupled with the            distal end portion of the elongate manipulation member, the            mesh having a plurality of cells in a tubular configuration            and being compressible to a collapsed configuration for            delivery to an endovascular treatment site through a            catheter and being self-expandable from the collapsed            configuration to an expanded configuration, and the mesh            comprising at least one galvanic cell;    -   expanding the mesh into at least a portion of the thrombus;    -   galvanically assisting attachment of at least a portion of the        thrombus to the mesh; and    -   removing the medical device from the blood vessel with at least        the attached portion of the thrombus.

21. The method of Clause 20, wherein the galvanic cell is activated inthe blood vessel.

22. The method of Clause 21, wherein the galvanic cell is activatedwhile the mesh is engaged with the thrombus.

23. The method of Clause 20, wherein galvanically assisting attachmentof at least a portion of the thrombus comprises binding, through agalvanic reaction, blood constituents to an anode of the galvanic cell.

24. The method of Clause 23, wherein the blood constituents are boundprimarily to an inwardly facing surface of the mesh.

25. The method of Clause 24, wherein the blood constituents are boundsubstantially only to an inwardly facing surface of the mesh.

26. The method of Clause 20, wherein the blood vessel comprises anintracranial blood vessel.

27. The method of Clause 20, wherein inserting the medical devicecomprises inserting it to a location laterally adjacent to at least aportion of the thrombus.

Additional features and advantages of the subject technology will be setforth in the description below, and in part will be apparent from thedescription, or may be learned by practice of the subject technology.The advantages of the subject technology will be realized and attainedby the structure particularly pointed out in the written description andclaims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the subject technology asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide furtherunderstanding of the subject technology and are incorporated in andconstitute a part of this description, illustrate aspects of the subjecttechnology and, together with the specification, serve to explainprinciples of the subject technology.

FIG. 1 illustrates a device, including an expandable member, for bloodflow restoration, thrombus removal, or both, according to an embodiment.

FIG. 2 illustrates an expandable member, according to an embodiment, inan unrolled state.

FIG. 3 is a schematic illustration of overlap configurations of theexpandable member of FIG. 2, as viewed from a distal end of theexpandable member.

FIGS. 4A-D are schematic illustrations of overlap configurations of theexpandable member of FIG. 2, as viewed from a side of the expandablemember.

FIG. 5 illustrates an expandable member in an unrolled state.

FIGS. 6A and 6B illustrate change in lateral cell width for variouslocations along expandable members.

FIGS. 7A and 7B illustrate associated contact reaction stress of theclot for various locations along expandable members, as a consequence ofthe change in lateral cell width illustrated in FIGS. 6A-6B.

FIG. 8 illustrates an expandable member, according to an embodiment, inan unrolled state.

FIG. 9 illustrates an expandable member, according to an embodiment, inan unrolled state.

FIG. 10 illustrates an expandable member, according to an embodiment, inan unrolled state.

FIGS. 11-14 are schematic plan views of various embodiments of galvanicregions for use with the endovascular device of FIG. 2.

FIGS. 15-20 are schematic cross-sections of filaments, according tovarious embodiments.

FIGS. 21A-21D schematically illustrate thrombi located in various vesselarrangements.

FIG. 22 schematically illustrates a system for blood flow restoration,thrombus removal, or both.

FIGS. 23-32 are cross-sectional views of a vessel and illustrate use ofa device according to some embodiments.

DETAILED DESCRIPTION

The detailed description set forth below is intended as a description ofvarious configurations of the subject technology and is not intended torepresent the only configurations in which the subject technology may bepracticed. The appended drawings are incorporated herein and constitutea part of the detailed description. The detailed description includesspecific details for the purpose of providing a thorough understandingof the subject technology. However, the subject technology may bepracticed without these specific details. For example, although somedrawings show the implementation of a galvanic effect in embodiments ofan expandable member 102, the present disclosure encompasses theimplementation of a galvanic effect in other endovascular devices, or inany thrombectomy device. In some instances, well-known structures andcomponents are shown in block diagram form in order to avoid obscuringthe concepts of the subject technology.

FIG. 1 depicts a medical device 100 according to some embodiments of thesubject technology. As illustrated in FIG. 1, the medical device 100 cancomprise an engagement member such as the expandable member 102, and amanipulation member 104. A proximal end portion of the expandable member102 and a distal end portion of the manipulation member 104 can bejoined at a connection 106. The manipulation member 104 can extendthrough a catheter 107 such that an operator can manipulate theexpandable member 102, positioned within and/or distal to a distal endof the catheter 107, using the manipulation member 104 at a locationproximal to a proximal end of the catheter 107.

The manipulation member 104 can have a length sufficient to extend froma location outside the patient's body through the vasculature to atreatment site within the patient's body. The manipulation member 104can be monolithic or formed of multiple joined components. In someembodiments, the manipulation member 104 can comprise a wire or acombination of wire(s), coil(s), and/or tube(s). The manipulation member104 can comprise one or more markers, e.g., comprised of radiopaquematerial(s) to aid radiographic visualization during manipulation.

The expandable member 102 and the manipulation member 104 can besubstantially permanently attached together at the connection 106. Thatis, the expandable member 102 and the manipulation member 104 can beattached together in a manner that, under the expected use conditions ofthe assembly 100, the endovascular device and the manipulation memberwould not become unintentionally separated from one another.

Depending on the procedure and intended use of the medical device 100,it optionally may be advantageous to have a connection mechanism thatpermits intentional release of the medical device 100. For example,during a blood flow restoration procedure, it may prove difficult and/ordangerous to fully retrieve a thrombus due to a complicated vasculatureor the risk of damaging a lumen wall. Leaving the medical device 100inside the patient may prove to be the only option available to asurgeon or other medical personnel, or it may be a goal of theprocedure, such as when the device 100 is deployed across an aneurysm(e.g., as an aneurysm bridge to retain coils or other materials in ananeurysm). In other circumstances the medical device 100 may includedrug-eluting capabilities, and/or may be coated with a particular typeof drug that facilitates thrombus dissolution. It may be advantageous insuch circumstances to release the medical device 100 and allow themedical device 100 to anchor the thrombus against the lumen wall whilethe thrombus is dissolved by the drug. In some embodiments, the medicaldevice 100 can comprise a portion, located proximally or distally of theconnection 106, that is configured for selective detachment of theendovascular device 102 from the manipulation member 104. For example,such a portion can comprise an electrolytically severable segment of themanipulation member. In some embodiments, the assembly 100 can be devoidof any feature that would permit selective detachment of theendovascular device 102 from the manipulation member 104.

Further details regarding connections that can be employed between theexpandable member 102 and the manipulation member 104 disclosed in U.S.Patent Publication No. 2014/0194919, entitled Connection of anEndovascular Intervention Device to a Manipulation Member, published onJul. 10, 2014; and U.S. Patent Publication No. 2014/0194911, entitledConnection of a Manipulation Member, Including a Bend withoutSubstantial Surface Cracks, to an Endovascular Intervention Device,published on Jul. 20, 2014; and U.S. patent application Ser. No.14/026,302, entitled Endovascular Device Engagement, filed on Sep. 13,2013; the entirety of each of which is hereby incorporated by referenceherein.

FIG. 2 is a plan view showing an embodiment of the expandable member 102in an unrolled state to facilitate description and understanding. Asillustrated in FIGS. 1 and 3, the expandable member 102 can have atubular or generally cylindrical shape in absence of external forces insome embodiments. The expandable member 102 can be self-expanding, e.g.by super-elasticity or shape memory, or expandable in response to forcesapplied on the expandable member, e.g. by a balloon.

As illustrated in FIGS. 1 and 2, the expandable member 102 can comprisea frame 108 having a proximal end 110 and a distal end 112. The framecan optionally comprise a plurality of struts 114; the struts 114 canoptionally be configured to define a plurality of cells 116 and/or forma mesh. Groups of longitudinally and serially interconnected struts 114can form undulating members 118 that extend in a generally longitudinaldirection. The struts 114 can be connected to each other by joints 120.While the struts are shown having a particular undulating or sinuousconfigurations, in some embodiments the struts can have otherconfigurations. The frame can have a generally tubular or generallycylindrical shape with one or both of the proximal end 110 and thedistal end 112 being open.

As illustrated in FIGS. 1 and 2, a proximal portion 122 of theexpandable member 102 can be tapered toward the proximal end 110. Insome embodiments, the taper of the proximal portion can advantageouslyfacilitate retraction and repositioning of the device 10 and expandablemember 102. In some embodiments, the tapered proximal portion can alsobe designed to generally not contact the vessel wall during a blood flowrestoration procedure, and to generally not interfere with the flow ofblood within a vessel.

Individual cells of the proximal portion 122 can have different sizesthan individual cells located distal to the tapered proximal portion.For example, in some embodiments, the proximal portion 122 can haveindividual cells that have a size larger than that of the individualcells located distal to the tapered proximal portion. The proximalportion 122 can taper gradually towards the connection 106.

The taper of proximal portion 122 can be at various angles relative tothe manipulation member 104. For example, in some embodiments, the tapercan have an angle of approximately 45 degrees relative to themanipulation member, though other angles are also possible.

The expandable member 102 can comprise a first edge 124 and a secondedge 126. The first edge 124 and second edge 126 can be formed, forexample, from cutting a sheet or a tube. While the first and secondedges are shown as having an undulating, or sinuous configuration, insome embodiments the first and second edges can have a straight, orlinear configuration, or other configuration. In some embodiments, theedges 124, 126 can be curved, straight, or a combination thereof alongthe tapered proximal portion 122.

The various embodiments of the expandable member 102 that are depictedor described herein provide one type of endovascular device orengagement member that may be employed as part of the medical device100, for example coupled to a distal end or portion of the manipulationmember 104, for functions such as removal or clots, thrombus or otherobstructions from the body. The engagement member can be expandable(either self-expandable or not), or non-expandable. The engagementmember can be generally tubular (as in the depicted expandable member102) in its deployed state, or it can have other forms when deployed.The engagement member can optionally form a mesh (as in the depictedexpandable member 102), or it can have other structural configurations.The engagement member, when deployed, can form a body that extends alonga central longitudinal axis that can be generally aligned or coincidentwith a central longitudinal axis of the manipulation member 104, and/orwith a central longitudinal axis of the vessel in which the engagementmember is deployed. The engagement member body can form an outer surfacehaving (a) an outward-facing portion that faces radially outward, awayfrom any one or more of the central longitudinal axes specified above,(b) an inward-facing portion that faces radially inward, toward any oneor more of the central longitudinal axes specified above, and/or (c) alaterally-facing portion that faces in a direction generally parallel toany one or more of the central longitudinal axes specified above.Therefore, the discussion provided elsewhere herein regarding thepresence or disposition of metals that can provide a galvanic effect(e.g., a first metal and a second metal, or an anodic metal and acathodic metal), and the various described embodiments, configurationsand alternatives for implementing such concepts, apply to the engagementmember as well, and accordingly such a galvanic effect can be providedin or on the engagement member.

Referring to FIGS. 3 and 4A-D, the expandable member 102 can be curled,rolled, or otherwise formed such that first edge 124 and second edge 126overlap one another when the expandable member 102 is in avolume-reduced form. In a volume-reduced form, the frame 102 of theexpandable member 102 can overlap to facilitate introduction of theexpandable member 102 into and through the catheter 107. In someembodiments, the expandable member 102 is circumferentially continuous(e.g., forming a continuous cylindrical shape), lacking first and secondedges 124, 126 and having no overlap or gap in a volume-reduced form andexpanded form. Regardless of whether the expandable member iscircumferentially continuous, the expandable member 102 can have acentral longitudinal axis both while in a volume-reduce form and whenfully or partially expanded. In some embodiments, the expandable member102 can be self-expandable, and can expand toward a fully expandedconfiguration upon release from the catheter 107. Upon expansion, theexpandable member 102 can expand towards an inner wall of a vessel,towards a thrombus occluding the inner wall of a vessel, or both.

FIGS. 4A-4D illustrate various amounts of overlap of the frame 108 ofthe expandable member 102. The extent of any overlap of the frame 108can depend upon a degree of the frame's expansion. Expansion within avessel can be limited, at least in part, by the vessel's size, and theamount and the properties of any thrombus present. For example, agreater overlap of the edges 124, 126 can occur in narrower vessels,whereas in wider vessels the overlap can be smaller, or even an“underlap” may occur, in which case the edges 22 and 24 are separated byan open gap or space within the vessel.

With continued reference to FIGS. 3 and 4A-D, embodiments of theexpandable member 102 can experience various degrees of overlap in avolume-reduced form, forming zones of overlap 128. The expandable member102 can assume various diameters Δ₁, Δ₂, etc., depending on the degreeof the overlap (e.g. represented by angle α₁, α₂, etc.). As illustratedin FIGS. 4A-D, the overlap zones 128 can vary in size and configurationdepending on the vessel size. When inside a vessel, the overlap zone ofthe expandable member 102 can advantageously provide grip and/orretaining ability with respect to a thrombus. For example, when theexpandable member 102 expands against a thrombus, the individual struts114 and individual cells 116 of the overlap zone can embed into andgrip, or retain, the thrombus. Alternatively, the expandable member 102can be constructed without any overlap or edges 124, 126, e.g. as acontinuous tubelike or cylindrical member.

The expandable member 102 can be manufactured in various lengths andrelaxed-state diameters. In some embodiments, the expandable member 102can have lengths, measured proximally to distally along the longitudinalaxis, of 15 mm or less to 40 mm or more, though other ranges and sizesare also possible. The expandable member 102 can also have relaxed-statediameters, the diameters being measured when the expandable member 102is fully free to expand, i.e., in absence of external forces. In someembodiments, the expandable member 102 can have a diameter ofapproximately 3 mm to 4 mm so as to be used in size 18 microcatheters(i.e. microcatheters with an inner diameter of approximately 0.21 inch).In some embodiments the expandable member 102 can have a diameter ofapproximately 5 mm to 6 mm so as to be used in size 27 microcatheters(i.e. microcatheters with an inner diameter of approximately 0.027inch). Other ranges and values are also possible.

Each cell 116 of the expandable member 102 can have a maximum length(labeled “L” in FIG. 2), as measured along a longitudinal axis of theexpandable member 102, and a maximum width W, as measured along adirection generally perpendicular to the length (labeled “W” in FIG. 2).In some embodiments, cell size and dimensions can vary, as can theindividual filament thicknesses and widths.

The location and longitudinal extent of thrombus engagement by amechanical thrombus-retrieval device, e.g., the expandable member 102,can affect the likelihood of successfully capturing the engagedthrombus. Some embodiments of the subject technology increase thelikelihood of successful thrombus capture and retrieval by increasing alongitudinal extent of substantially even thrombus engagement, distallyshifting the region of increased thrombus engagement, or both. When athrombus is primarily engaged along a portion of the thrombus near itsproximal end, and particularly when a longitudinal extent ofsubstantially even thrombus engagement is small, the thrombus may bemore likely to fragment, become released from the retrieval device, orboth.

In some embodiments, the expandable member 102 can be configured forsubstantially uniform or distally biased thrombus engagement, afterexpansion of the expandable member 10 into the thrombus, duringretrieval of thrombus from a vessel by proximal retraction of themanipulation member 104. The thrombus can be generally soft, ormalleable, or generally hard, or callous. For example, the expandablemember 102 can have strut and cell dimensions that provide substantiallyuniform or distally biased thrombus engagement.

FIG. 5 illustrates an expandable member 102 having a pattern 130 ofcells 116 of substantially uniform dimensions and of struts 114 ofsubstantially uniform dimensions. The pattern of cells and struts ofFIG. 5 is substantially uniformly flexible or deformable. However, whenthe expandable member of FIG. 5 is embedded in a thrombus and aproximally directed force is applied at a proximal end 110 of theexpandable member, the cells of the expandable member tend to collapsein width, and therefore engage a thrombus, more along a proximal portionof the substantially uniform pattern 130 than they do along a distalportion of the substantially uniform pattern 130. Such a proximallydirected force may be considered to simulate the force exerted on theproximal end 110, via the manipulation member 104, during retrieval ofthe expandable member 102 in a procedure to remove, e.g., thrombus froma blood vessel.

FIGS. 6A and 6B illustrate the amount of change (reduction) in (e.g.,maximum) cell width W observed for cells in various longitudinalpositions along the length of the frame 108, upon application of aproximally directed force at a proximal end of the frame when embeddedin simulated thrombus having an outer extent fixed in six degrees offreedom. FIG. 6A is an exemplifying plot of the amount of change(reduction) in (maximum) cell width (resulting from such forceapplication) against longitudinal position for a frame having asubstantially uniform cell angle or pattern 130. As indicated by FIG.6A, the amount of change in maximum cell width diminishes with distancefrom the proximal end for a frame having a substantially uniform pattern130. Thus, an expandable member having a substantially uniform pattern130 “pinches” the thrombus more (by virtue of a greater reduction incell width) along a proximal portion of the thrombus than it does alonga distal portion of the thrombus.

FIG. 6B is an exemplifying plot of the amount of change (reduction) in(maximum) cell width against the longitudinal position for frames insome embodiments of the subject technology, for example such as thoseillustrated in FIGS. 2, 8, 9, and 10. In contrast to FIG. 6A, FIG. 6Bindicates that the amount of reduction in maximum cell width increaseswith distance from the proximal end for frames according to someembodiments of the subject technology. Thus, an expandable memberaccording to some embodiments of the subject technology pinches andgrips the thrombus more along a distal portion of the thrombus than itdoes along a proximal portion of the thrombus. Therefore, expandablemembers according to some embodiments of the subject technology can beless likely to fragment the thrombus, release the thrombus, or bothduring retrieval, compared to an expandable member having asubstantially uniform pattern 130.

FIGS. 7A and 7B indicate the resultant contact reaction stresses (due tothe cell width reduction) between the frame and thrombus in cells atvarious longitudinal positions along the length of the frame, uponapplication of a proximally directed force at a proximal end of theframe when embedded in simulated thrombus having an outer extent fixedin six degrees of freedom. FIG. 7A is an exemplifying plot of contactreaction stress against longitudinal position for a frame, asillustrated in FIG. 5 for example, wherein longitudinally and laterallyadjacent cells have substantially the same dimensions and the strutssurrounding those cells have substantially the same dimensions. Asindicated by FIG. 7A, contact reaction stress diminishes with distancefrom the proximal end for a frame having a substantially uniform pattern130. Thus, an expandable member having a substantially uniform pattern130 tends to pull on the thrombus, during retraction, more along aproximal portion of the thrombus than it does along a distal portion ofthe thrombus.

FIG. 7B is an exemplifying plot of contact reaction stress againstlongitudinal position for frames in some embodiments of the subjecttechnology, for example such as those illustrated in FIGS. 2, 8, 9, and10. In contrast to FIG. 7A, FIG. 7B indicates that contact reactionstress increases, along at least a portion of the frame's length, withdistance from the proximal end for frames according to some embodimentsof the subject technology. Thus, an expandable member according to someembodiments of the subject technology tends to pull on the thrombus lessalong a proximal portion of the thrombus than it does along a portion ofthe thrombus distal to the proximal portion. Therefore, expandablemembers according to some embodiments of the subject technology can beless likely to fragment the thrombus, release the thrombus, or bothduring retraction, compared to an expandable member having asubstantially uniform pattern 130.

FIGS. 8-10 illustrate expandable members 102, according to embodimentsof the subject technology, in plan view, e.g., an unrolled state. Theexpandable members 102 of FIGS. 8-10 are examples of the expandablemember 102 described above with reference to FIGS. 2-4D. Accordingly,the description of the expandable member 102 with reference to FIGS.2-4D also applies to expandable members 102 of FIGS. 8-10.

The expandable members 102 of FIGS. 8-10 can provide distally biasedthrombus engagement, as described above with reference to FIGS. 6Band/or 7B, substantially uniform thrombus engagement, or a combinationthereof over lengthwise portions of the expandable member. Thrombusengagement can be considered substantially uniform when the amount ofchange in maximum cell width and/or contact reaction stress varies inthe longitudinal direction by less than 5% upon application of aproximally directed force at a proximal end of the expandable memberwhen the expandable member is embedded in thrombus, or simulatedthrombus, having an outer extent fixed in six degrees of freedom.

In some embodiments, at least a portion of the frame 108, from a firstlocation to a second location along the frame, is configured such thatan amount of cell deformation or deflection in response tolongitudinally directed tensile forces decreases by less than 5% orincreases in a distal direction along a portion of the frame. The celldeformation can be, for example, change of maximum cell width. In someembodiments, the amount of cell deformation in response tolongitudinally directed tensile forces does not decrease in a distaldirection along the portion of the frame. In some embodiments, theamount of cell deformation in response to longitudinally directedtensile forces continuously increases in a distal direction along theportion of the frame. The portion of the frame can extend from a firstlocation to a second location along the frame. In some embodiments, thefirst and second locations can be longitudinally separated by a distancethat is more than half of the mesh length, at least two thirds of theframe length, at least three quarters of the frame length, or at least90% of the frame length. In some embodiments, portion of the frame cancomprise a longitudinal row of at least two, three, or four cells.

In some embodiments, at least a portion of the frame 108, from a firstlocation to a second location along the frame, is configured such thatan amount of thrombus engagement in response to longitudinally directedtensile forces decreases by less than 5% or increases in a distaldirection along a portion of the frame. The thrombus engagement can be,for example, contact reaction stress. In some embodiments, the amount ofthrombus engagement in response to longitudinally directed tensileforces does not decrease in a distal direction along the portion of theframe. In some embodiments, the amount of thrombus engagement inresponse to longitudinally directed tensile forces continuouslyincreases in a distal direction along the portion of the frame. Theportion of the frame can extend from a first location to a secondlocation along the frame. In some embodiments, the first and secondlocations can be longitudinally separated by a distance that is morethan half of the mesh length, at least two thirds of the frame length,at least three quarters of the frame length, or at least 90% of theframe length. In some embodiments, portion of the frame can comprise alongitudinal row of at least two, three, or four cells.

FIG. 8 illustrates an expandable member 102 wherein, in a portion of theframe 108 in a relaxed state, each cell distally adjacent to anothercell, in a longitudinal row of cells, has a larger proximal inscribedstrut angle θ between first and second struts (i) bounding a proximalportion of the cell and (ii) diverging in a distal direction, than hasthe another cell. For example, FIG. 8 shows a first cell 132 having aproximal inscribed strut angle θ₁, a second cell 134 having a proximalinscribed strut angle θ₂, a third cell 136 having a proximal inscribedstrut angle θ₃, and a fourth cell having a proximal inscribed strutangle θ₄, wherein θ₄>θ₃>θ₂>θ₁. The portion of the frame can extend froma first location to a second location along the frame. In someembodiments, the first and second locations can be longitudinallyseparated by a distance that is more than half of the mesh length, atleast two thirds of the frame length, at least three quarters of theframe length, or at least 90% of the frame length. In some embodiments,portion of the frame can comprise a longitudinal row of at least two,three, or four cells.

In some embodiments, the proximal inscribed strut angle θ can bemeasured between substantially straight portions 140 of the struts 114,as illustrated in FIG. 8. In some embodiments, the proximal inscribedstrut angle θ can be measured between straight reference lines thatconnect a joint 120 a, at a proximal end of a cell, with opposinglaterally positioned joints 120 b, 120 c, respectively, at of that cell.In either case, each strut 114 can be straight, curved, or comprisestraight portion(s) and curved portion(s).

In addition or alternative to distally increasing, proximal inscribedstrut angles, the expandable member 102 can have a portion of the frame108 wherein, in a relaxed state, each cell distally adjacent to anothercell, in a longitudinal row of cells, has a larger interior bounded areathan has the another cell. For example, an interior bounded area offourth cell 138 can be larger than an interior bounded area of thirdcell 136, which can be larger than an interior bounded area of secondcell 134, which can be larger than an interior bounded area of firstcell 132. The portion of the frame can extend from a first location to asecond location along the frame. In some embodiments, the first andsecond locations can be longitudinally separated by a distance that ismore than half of the mesh length, at least two thirds of the framelength, at least three quarters of the frame length, or at least 90% ofthe frame length. In some embodiments, portion of the frame can comprisea longitudinal row of at least two, three, or four cells.

In some embodiments, the expandable member 102 can have a portion of theframe 108 wherein, in a relaxed state, each cell distally adjacent toanother cell, in a longitudinal row of cells, has a larger maximum cellwidth W than has the another cell. For example, a maximum cell width offourth cell 138 can be larger than a maximum cell width of third cell136, which can be larger than a maximum cell width of second cell 134,which can be larger than a maximum cell width of first cell 132. Theportion of the frame can extend from a first location to a secondlocation along the frame. In some embodiments, the first and secondlocations can be longitudinally separated by a distance that is morethan half of the mesh length, at least two thirds of the frame length,at least three quarters of the frame length, or at least 90% of theframe length. In some embodiments, portion of the frame can comprise alongitudinal row of at least two, three, or four cells.

Accordingly, the herein-discussed configurations of the expandablemember 102 (distally increasing maximum cell width W, distallyincreasing cell area, distally increasing proximal included strut angleθ, distally increasing amplitude A, distally diverging reference lines144, and/or distally increasing strut flexibility/deflectability) caneach be considered a means for engaging a thrombus (or other material)in a substantially uniform (and/or distally biased) manner along thelength of the expandable member 102.

In the embodiment of FIG. 8, maximum cell length can range from 3.50 mmto 5.50 mm in a relaxed state, though other ranges and values are alsopossible, and maximum cell width can range from between 2.50 mm to 4.50mm and a relaxed state, though other ranges and values are alsopossible. All of the foregoing dimensions can optionally be implementedalone or in any combination without departing from the scope of thisdisclosure.

FIG. 9 illustrates an expandable member 102 comprising a plurality ofundulating or sinuous members 118. Each undulating or sinuous member 118can comprise a plurality of oscillations 142. Each oscillation can havean amplitude (labeled “A” in FIG. 9). In some embodiments, anoscillation can correspond in length to the length of a cell. Anoscillation 142 can comprise one or more struts 114. Some embodimentscan comprise a portion of the frame 108 wherein, in a relaxed state,each oscillation of each undulating or sinuous member 118 does notdecrease, or alternatively, increases in a distal direction compared toa proximally adjacent oscillation. In some embodiments, the amplitude ofthe oscillations can increase distally at a constant rate per unitlength. The portion of the frame can extend from a first location to asecond location along the frame. In some embodiments, the first andsecond locations can be longitudinally separated by a distance that ismore than half of the mesh length, at least two thirds of the framelength, at least three quarters of the frame length, or at least 90% ofthe frame length. In some embodiments, portion of the frame can comprisea longitudinal row of at least two, three, or four cells.

FIG. 9 illustrates a plurality of reference lines 144. Each referenceline can pass through all joints 120 between adjacent cells in a row ofcells. Some embodiments can comprise a portion of the frame 108 wherein,in a relaxed state, each reference line 144 continuously diverges fromat least one or two adjacent reference lines 144. In some embodiments,the reference lines can be straight. In some embodiments, all or aportion of respective reference line can be curved. The portion of theframe can extend from a first location to a second location along theframe. In some embodiments, the first and second locations can belongitudinally separated by a distance that is more than half of themesh length, at least two thirds of the frame length, at least threequarters of the frame length, or at least 90% of the frame length. Insome embodiments, the portion of the frame can comprise a longitudinalrow of at least two, three, or four cells.

In some embodiments, the expandable member 102 can have a portion of theframe 108 wherein, in a relaxed state, each cell distally adjacent toanother cell can have a strut that is more flexible or deflectable thana strut of the another cell. In some embodiments, each strut distallyadjacent to another strut can be more flexible or deflectable than isthe another strut. Strut flexibility or delectability can be increased,for example, by diminishing strut thickness, strut width, or both alongall or a portion of the strut's length. The portion of the frame canextend from a first location to a second location along the frame. Insome embodiments, the first and second locations can be longitudinallyseparated by a distance that is more than half of the mesh length, atleast two thirds of the frame length, at least three quarters of theframe length, or at least 90% of the frame length. In some embodiments,portion of the frame can comprise a longitudinal row of at least two,three, or four cells.

The struts 114 can have individual strut widths “a” (FIG. 10) that rangefrom 0.010 in. to 0.025 in., and individual strut thicknesses “b” thatrange from 0.045 mm to 0.080 mm, though other ranges and values forindividual strut width and thickness are also possible. Widths “a” asdescribed herein can generally be measured as illustrated by the arrowsin FIG. 10. Thicknesses “b” as described herein can generally bemeasured as illustrated by the arrows in FIG. 3 (e.g. in a directionextending out of the page of FIG. 10, and perpendicular to themeasurement for width “a”). The widths “a” can be measured, for example,using a system such as the Visicon Automated Inspection System, or othersuitable system. The thicknesses “b” can be measured, for example, usinga system such as the Heidenhain Inspection System, or other suitablesystem.

With continued reference to FIG. 10, the joints 120 can have anindividual strut thickness “b” that range from 0.050 mm to 0.0825 mm andan individual strut width “a” that ranges from 0.050 mm to 0.0825 mm,though other ranges and values are also possible. In some embodiments,individual struts can have individual strut thicknesses “b” that rangefrom 0.040 mm to 0.075 mm, and individual strut widths “a” that rangefrom 0.038 mm to 0.082 mm, though other ranges and values are alsopossible. In some embodiments, the individual struts in a portion of theexpandable member 102 can have average strut thicknesses “b” that rangefrom 0.048 mm to 0.067 mm, and individual strut widths “a” that averagefrom 0.053 mm to 0.067 mm, though other ranges for average values arealso possible.

FIG. 10 illustrates an example of an embodiment wherein strut thicknessis diminished in a distal direction, thereby distally increasing strutflexibility or to flexibility. The frame 108 of the expandable member102 in FIG. 10 comprises a plurality of rings 146, 148, 150, 152, 154,156, 158 of circumferentially adjacent struts. The struts 114 in eachring can have substantially the same width, as illustrated, for example,in FIG. 10. In some embodiments, circumferentially adjacent struts canhave different widths. Referring again to FIG. 10, the strut width ofeach ring 146, 148, 150, 152, 154, 156, 158 can diminish in the distaldirection. In other words, a strut width of ring 158 can be less than astrut width of ring 156, which can be less than a strut width of ring of154, which can be less than a strut width of ring 152, which can be lessthan a strut width of ring 150, which can be less than a strut width ofring 148, which can be less than a strut width of ring 146. In someembodiments, two or more longitudinally adjacent struts, or rings ofstruts, can have the same, or substantially the same, width. Forexample, struts 114 distal to the ring 158 can have the same, orsubstantially the same, strut width as the struts of ring 158.

Although FIG. 10 illustrates the struts 114 as having substantiallyconstant widths along their entire respective lengths, the struts canhave widths that vary along their lengths in some embodiments. Forexample, the struts can have an hourglass shape, can be wider in themiddle than at the ends, can have corrugated edges, or have otherconfigurations. Strut thickness can likewise be constant or variablealong each strut's length. The struts' cross-sectional areas canlikewise be constant or variable along each strut's length.

In the embodiment of FIG. 10, maximum cell length can range from 3.50 mmto 5.50 mm in a relaxed state, though other ranges and values are alsopossible and within the scope of this disclosure, and maximum cell widthcan range from between 2.50 mm to 4.50 mm and a relaxed state, thoughother ranges and values are also possible and within the scope of thisdisclosure.

The expandable member 102 can generate specific forces once it isdeployed and released from the catheter 107 for engagement and removalof thrombi. By deploying the expandable member 102 in or across athrombus, the expandable member 102 can be expanded, e.g., self-expandedto a larger diameter due to elastic energy stored in the expandablemember 102. The expandable member 102 can expand in the vessel untilequilibrium is reached between the stored elastic energy and an opposingforce from the surrounding vessel wall and/or thrombus. The struts 114and cells 116 of the expandable member 102 can penetrate a thrombus,promoting adhesion and embedment of the thrombus to the expandablemember 102, and the expanding force of the expandable member 102 canpromote dislodgment of the thrombus from the vessel wall.

In some embodiments, the expandable member 102 can further include atleast one distal marker 160. The distal marker 160 can be attached to orintegrally formed with a distal portion of the expandable member 102.The distal marks 160 can comprise, for example, a band comprisingplatinum, gold, and/or other radiopaque materials. The markers 160 canbe used during an imaging process to identify a location or locations ofthe expandable member 102 during a blood flow restoration procedure. PCTPublication No. WO 2009/105710, which is incorporated by reference inits entirety, describes various uses of marker bands and imaging of anexpandable member 102.

The frame 108 can be formed, for example, by cutting a sheet or tube(e.g., by laser, etching, etc.), by interconnecting a multitude offilaments by laser welding, or by other suitable methods. In someembodiments, the expandable member 102 can be initially laser cut from atube. In some embodiments, the expandable member 102 can be formed bycutting a pattern on a flat sheet and then rolling the flat sheet into agenerally tube-like or coiled shape. The joints 120 may be formed bywelding, soldering, or otherwise joining the struts 114. Other methodsfor forming the expandable member 102 are also possible.

In some embodiments, the endovascular device, engagement member orexpandable member 102 can comprise metal, polymer, ceramic, permanentenduring materials, and may comprise either of or both ofnon-bioabsorbable and bioabsorbable materials. Exemplary materialsinclude, but are not limited to, NITINOL®, stainless steel, cobaltchromium alloys, Elgiloy, magnesium alloys, polylactic acid, polyglycolic acid, poly ester amide (PEA), poly ester urethane (PEU), aminoacid based bioanalogous polymers, tungsten, tantalum, platinum,polymers, bio-polymers, ceramics, bio-ceramics, or metallic glasses. Insome embodiments, the expandable member may be formed from materialshaving shape memory properties. Where a galvanic effect is desired, theendovascular device, engagement member or expandable member 102 shouldbe formed from metal, or from a non-metal that is coated with metal.

In some embodiments, the endovascular device, engagement member orexpandable member 102 can have a galvanic cell or a plurality ofgalvanic cells formed on a surface thereof. Such galvanic cell(s) cangenerate, in the presence of blood, thrombus, or other electrolyticmedium, a voltage and/or electrical charge that enhances the capabilityof the expandable member 102 to grip thrombus. For example, the galvaniccell(s) can generate an electrical charge, or electrically chargedregion(s), on the endovascular device, engagement member or expandablemember 102 that can attract, adhere, and/or attach thrombus to theexpandable member 102 when the expandable member 102 is deployed next toor into thrombus in a blood vessel. The generated charge or chargedregions on the expandable member 102 can have a charge opposite that ofconstituents of the thrombus. The generated charge or charged regionscan include both regions of negative charge and regions of positivecharge, each of which can attract, adhere, and/or attach to bloodconstituents or thrombus constituents of the opposite charge. Theattraction, adhesion, and/or attachment of blood constituents tothrombus constituents may be electrostatic.

The galvanic cell(s) can comprise at least two different metals (as usedherein, “metal” can refer to a pure or elemental metal, or to alloys),such as a first metal 180 and a second metal 182, that generate anelectrical charge in the presence of an electrolytic medium, forexample, such as blood. The metals may be characterized as havingdifferent reduction potentials or electrode potentials; various metalcombinations may be determined with reference to the electromotive force(EMF) chart. The metals of the galvanic cell are in electrical contact,e.g., direct physical contact, with each other. The first metal 180 andsecond metal 182 can be selected to induce a galvanic voltage and imparta desired charge arrangement in a galvanic region. For example, themetals 180, 182 can be selected so that the first metal 180 functions asa cathode (having a positive charge) and the second metal 182 functionsas an anode (having a negative charge), or vice versa. Any combinationof anode and cathode metals can be employed. One useful combination is afirst metal of nickel-titanium alloy, e.g., nitinol, and a second metale.g. of magnesium, in which case the first metal can act as a cathodeand as the structural metal of the endovascular device, engagementmember or expandable member 102, and the second metal can act as ananode. The reverse can be employed as well, in which the first metal ismagnesium and the second metal is nitinol.

In a single cell the nitinol-magnesium combination can induce a galvanicvoltage of about 1.3 volts in saline. Other strongly anodic metals canbe used as a first or second metal in combination with nitinol, forexample lithium or zinc. Metals other than nitinol also can be used as acathode, such as, for example, platinum, nickel, titanium, gold,graphite, and silver. The structural metal of the endovascular device,engagement member or expandable member 102 can also be employed asanode, where a metal that is cathodic relative to the structural metalis employed as the second metal. In a single expandable member 102multiple types of first metals and/or multiple types of second metalscan be employed. For example, one second metal type can be employed inone portion of the expandable member 102 and another second metal typecan be employed in another portion of the expandable member 102. Metalcombinations other than nitinol-magnesium may induce galvanic voltagesdifferent than does nitinol-magnesium. For example, a galvanic cellcomprising nitinol and platinum can induce a galvanic voltage of about0.49 volts in saline, and a galvanic cell comprising magnesium andplatinum can induce a galvanic voltage of about 1.7 volts in saline.

FIGS. 11-14 illustrate several embodiments of the expandable member 102or a portion of filament(s) 178 thereof, for example as in the area A-Ain FIG. 2, that include one or more galvanic cells. Such cells can beformed by providing a first metal 180 and a second metal 182 disposedover and in electrical contact, e.g., direct physical contact, with thefirst metal. The first metal 180 can comprise, for example, the metalfrom which the frame 108 is or filaments 178 are fabricated. Forexample, when the expandable member 102 is laser cut from a nitinoltube, the first metal 180 can comprise nitinol. For convenience herein,such a metal can be considered the “structural metal” of the frame 108,filaments 178 and/or expandable member 102. The first metal 180 canalternatively comprise a metal which is plated, coated, deposited, orotherwise applied over some or all of the structural metal (orstructural polymer) of the expandable member 102.

The second metal 182 can be coated, deposited, welded, plated, orotherwise applied over some or all of the structural metal (orstructural polymer where a metal-coated polymer is employed) of theexpandable member 102, which may be the first metal 180 or anothermetal. If the first metal 180 comprises a metal which is plated, coated,deposited, or otherwise applied over some or all of the structural metal(or structural polymer) of the expandable member 102, the second metal182 can comprise the structural metal of the expandable member 102 orcan be plated, coated, deposited, or otherwise applied over some or allof the structural metal (or structural polymer), which is neither thefirst metal nor the second metal.

As seen in FIGS. 11-14, the second metal 182 can be arranged in anintermittent pattern of one or more discrete second metal regions on aregion of the first metal 180 (or alternatively in a continuous layerover at least a portion of the first metal 180). One or more portions ofthe structural metal (or structural polymer) can be masked or otherwisecovered (e.g., by a mandrel 186), for example as illustrated in FIG. 17,during plating, coating, deposition, or other application of the firstmetal, the second metal, or both on the structural metal (or structuralpolymer). The region of the first metal 180 can be continuous orgenerally continuous, including any portions thereof that underlie thesecond metal 182 regions. Accordingly, a galvanic region of theexpandable member 102 can comprise a pattern of one or multiple discretesecond metal 182 regions situated on or in a first metal 180 region,which first metal region can be continuous or generally continuous inthe area(s) in which the galvanic region prevails. The galvanic regioncan prevail, for example, over the entire outer surface of theendovascular device, engagement member or expandable member 102, or overa selected portion thereof, such as the mesh (where present), a distalportion 176 and/or the proximal portion 122 (see FIG. 1). The galvanicregion can prevail, for example, over any one or combination of thefollowing: (a) some or all of the portion of the outer surface of theendovascular device, engagement member or expandable member 102 thatfaces radially outward, away from the central longitudinal axis of theendovascular device, engagement member or expandable member 102, (b)some or all of the portion of the outer surface of the endovasculardevice, engagement member or expandable member 102 that faces radiallyinward, toward the central longitudinal axis of the endovascular device,engagement member or expandable member 102, and (c) some or all of theportion of the outer surface of the endovascular device, engagementmember or expandable member 102 that faces laterally toward the interiorof a cell 116, or otherwise. Instead of or in addition to the foregoing,the galvanic region can be configured such that one, some or all cell(s)116, and/or filament(s) 178, can have more than 1, 2, 3, 5, or 10galvanic cells positioned on it.

The locations (a), (b), and (c) are illustrated with respect to a singlefilament in FIGS. 15-18, which are schematic cross-sections of filaments178, for example as taken along line B-B in FIG. 12. Each of the rightand left directions in FIGS. 15-18 can be considered alternativelyradially inward or outward. Accordingly, FIGS. 15-18 illustratefilaments having the first metal 180 prevailing over location (a) or (b)and the second metal 180 prevailing over the other of location (a) or(b). In FIGS. 15 and 17, the second metal 182 also extends onto thelocation (a) or (b) on which the first metal 180 prevails, but theextension of the second metal on to such location is to a much smallerdegree such that such location is substantially free of the secondmetal. In FIGS. 16 and 18, the second metal 182 does not extend onto thelocation (a) or (b) on which the first metal 180 prevails, such thatsuch location is free of the second metal. FIGS. 15-18 also illustratethe filaments 178 having the first metal 180 and the second metal 180over location (c), although in different proportions. Thus, location (c)may overlap somewhat with locations (a) and/or (b) depending on theshape of the filament.

In a single endovascular device, engagement member or expandable member102 employing multiple types of first metals and/or multiple types ofsecond metals, (i) one first metal type can be employed in one portionof the expandable member 102 (e.g., one of the locations (a), (b), (c)specified above) and another first metal type can be employed in anotherportion of the expandable member 102 (e.g., another of the locations(a), (b), (c)), and/or (ii) one second metal type can be employed in oneportion of the expandable member 102 (e.g., one of the locations (a),(b), (c) specified above) and another second metal type can be employedin another portion of the expandable member 102 (e.g., another of thelocations (a), (b), (c)).

FIGS. 11-14 illustrate several embodiments that implement anintermittent pattern of discrete second metal regions 182, each in thecontext of a single filament 178 that can form one side of a cell 116wherein (for example) four filaments 178 border some or all cells 116.One, some or all of the filaments bordering a cell 116 can have any ofthe patterns shown in FIGS. 11-14, or other intermittent pattern(s).FIG. 11 shows a pattern in which second metal regions 182 in the form ofcircular disks, polygons or other shapes are distributed in a (regularor random) spotted pattern in the first metal region 180. The disks,polygons, etc. can be of uniform or non-uniform size and/or shape. FIG.12 shows a single second metal region 182 in the shape of a ring or bandthat can extend partially or completely around a filament 178. FIG. 13shows a pattern that is similar to that of FIG. 12 but with multiplesuch rings or bands. FIG. 14 shows a pattern in which the second metalregion 182 can take the form of one or more strips that extendlongitudinally along the filament 178. Generally, the thickness of thesecond metal can be adjusted to increase or decrease the duration of thegalvanic reaction.

In some embodiments, the second metal 182 can prevail in or cover someor all of the portion of the outer surface of the endovascular device,engagement member or expandable member 102 that faces radially outward,away from the central longitudinal axis of the endovascular device,engagement member or expandable member 102. For example, the secondmetal 182 can cover most or substantially all of such outward-facingsurface of the expandable member 102, or most or substantially all ofsuch outward-facing surface of the mesh, the distal portion 176, and/orthe proximal portion 122. In various embodiments, the second metal cancover at least 50%, at least 60%, at least 75%, at least 90%, at least95%, or at least 98% of any such outward-facing surface of theexpandable member 102, the mesh, the distal portion 176, and/or theproximal portion 122. Additionally or alternatively, substantially allof such outward-facing surface of the expandable member 102 (or of themesh, the distal portion 176, and/or the proximal portion 128) can becovered collectively by the second metal 182 in some areas and by somematerial other than the first metal 180 in other areas. In combinationwith any of the foregoing, the first metal 180 can cover, prevail in orbe exposed in some or all of the portion of the outer surface of theexpandable member 102 that faces radially inward, toward the centrallongitudinal axis of the expandable member 102 (or some or all of suchinward-facing surface of the mesh, the distal portion 176, or theproximal portion 122). In the embodiments under discussion in thisparagraph, the first metal can prevail substantially only on theinward-facing surface, and the second metal can prevail substantiallyonly on the outward-facing surface, of the expandable member 102, themesh, distal portion 176, or proximal portion 122. In some embodiments,at least 50%, at least 60%, at least 75%, at least 90%, at least 95%, orat least 98% of a total surface area of the second metal can be at theoutward-facing surface of the expandable member 102, the mesh, thedistal portion 176, and/or the proximal portion 122. In someembodiments, at least 50%, at least 60%, at least 75%, at least 90%, atleast 95%, or at least 98% of a total surface area of the first metalcan be at the inward-facing surface of the expandable member 102, themesh, the distal portion 176, and/or the proximal portion 122. In someembodiments, the first metal can be substantially absent from theoutward-facing surface, and/or the second metal can be substantiallyabsent from the inward-facing surface, of the expandable member 102, themesh, the distal portion 176 or proximal portion 122. In someembodiments, less than 50%, less than 40%, less than 25%, less than 10%,less than 5%, or less than 2% of a total surface area of the secondmetal can be at the inward-facing surface of the expandable member 102,the mesh, the distal portion 176, and/or the proximal portion 122. Insome embodiments, at least 50%, at least 60%, at least 75%, at least90%, at least 95%, or at least 98% of a total surface area of the secondmetal can be at other than the inward-facing surface of the expandablemember 102, the mesh, the distal portion 176, and/or the proximalportion 122. In some embodiments, less than 50%, less than 40%, lessthan 25%, less than 10%, less than 5%, or less than 2% of a totalsurface area of the first metal can be at the outward-facing surface ofthe expandable member 102, the mesh, the distal portion 176, and/or theproximal portion 122. In some embodiments, at least 50%, at least 60%,at least 75%, at least 90%, at least 95%, or at least 98% of a totalsurface area of the first metal can be at the other than theoutward-facing surface of the expandable member 102, the mesh, thedistal portion 176, and/or the proximal portion 122.

In some embodiments, the second metal 182 can prevail in or cover someor all of the portion of the outer surface of the endovascular device,engagement member or expandable member 102 that faces radially inward,away from the central longitudinal axis of the endovascular device,engagement member or expandable member 102. For example, the secondmetal 182 can cover most or substantially all of such inward-facingsurface of the expandable member 102, or most or substantially all ofsuch inward-facing surface of the mesh, the distal portion 176, and/orthe proximal portion 122. In various embodiments, the second metal cancover at least 50%, at least 60%, at least 75%, at least 90%, at least95%, or at least 98% of any such inward-facing surface of the expandablemember 102, the mesh, the distal portion 176, and/or the proximalportion 122. Additionally or alternatively, substantially all of suchinward-facing surface of the expandable member 102 (or of the mesh, thedistal portion 176, and/or the proximal portion 128) can be coveredcollectively by the second metal 182 in some areas and by some materialother than the first metal 180 in other areas. In combination with anyof the foregoing, the first metal 180 can cover, prevail in or beexposed in some or all of the portion of the outer surface of theexpandable member 102 that faces radially outward, toward the centrallongitudinal axis of the expandable member 102 (or some or all of suchoutward-facing surface of the mesh, the distal portion 176, or theproximal portion 122). In some of the embodiments under discussion inthis paragraph, the first metal can prevail substantially only on theoutward-facing surface, and the second metal can prevail substantiallyonly on the inward-facing surface, of the expandable member 102, themesh, distal portion 176, or proximal portion 122. In some embodiments,at least 50%, at least 60%, at least 75%, at least 90%, at least 95%, orat least 98% of a total surface area of the second metal can be at theinward-facing surface of the expandable member 102, the mesh, the distalportion 176, and/or the proximal portion 122. In some embodiments, atleast 50%, at least 60%, at least 75%, at least 90%, at least 95%, or atleast 98% of a total surface area of the first metal can be at theoutward-facing surface of the expandable member 102, the mesh, thedistal portion 176, and/or the proximal portion 122. In someembodiments, the first metal can be substantially absent from theinward-facing surface, and/or the second metal can be substantiallyabsent from the outward-facing surface, of the expandable member 102,the mesh, the distal portion 176 or proximal portion 122. In someembodiments, less than 50%, less than 40%, less than 25%, less than 10%,less than 5%, or less than 2% of a total surface area of the secondmetal can be at the outward-facing surface of the expandable member 102,the mesh, the distal portion 176, and/or the proximal portion 122. Insome embodiments, at least 50%, at least 60%, at least 75%, at least90%, at least 95%, or at least 98% of a total surface area of the secondmetal can be at other than the outward-facing surface of the expandablemember 102, the mesh, the distal portion 176, and/or the proximalportion 122. In some embodiments, less than 50%, less than 40%, lessthan 25%, less than 10%, less than 5%, or less than 2% of a totalsurface area of the first metal can be at the inward-facing surface ofthe expandable member 102, the mesh, the distal portion 176, and/or theproximal portion 122. In some embodiments, at least 50%, at least 60%,at least 75%, at least 90%, at least 95%, or at least 98% of a totalsurface area of the first metal can be at the other than theinward-facing surface of the expandable member 102, the mesh, the distalportion 176, and/or the proximal portion 122.

The endovascular device, engagement member or expandable member 102 (ormesh, or distal portion 176, or proximal portion 122) can have anoutward-facing surface that is purely or substantially purely cathodicor anodic, and an inward-facing surface that is purely or substantiallyof the opposite polarity. In some such embodiments, the outward-facingsurface is purely or substantially purely anodic and the inward-facingsurface is purely or substantially purely cathodic, by employing asecond metal of, e.g., zinc or magnesium that covers all orsubstantially all of the outward-facing surface and a first metal of,e.g., nitinol that covers all or substantially all of the inward-facingsurface. In some such embodiments, the inward-facing surface is purelyor substantially purely anodic and the outward-facing surface is purelyor substantially purely cathodic, by employing a second metal of, e.g.,zinc or magnesium that covers all or substantially all of theinward-facing surface and a first metal of, e.g., nitinol that coversall or substantially all of the outward-facing surface. The first metalcan comprise the structural metal of the endovascular device, engagementmember or expandable member 102, mesh, distal portion 176, or proximalportion 122. It may be useful to provide an outward-facing surface thatis purely or substantially purely anodic, for example, to attractpositively-charged thrombus and cause it to adhere to the outward-facingsurface, where the thrombus may more likely to detach from theendovascular device, engagement member or expandable member 102 duringremoval (in contrast to the interior of the expandable member). It maybe useful to provide an inward-facing surface that is purely orsubstantially purely anodic, for example, to attract positively-chargedthrombus and cause it to adhere to the inward-facing surface and/or toavoid attachment to the vessel wall.

As depicted in FIGS. 1 and 2, some or all of the cells 116 can be open(e.g., uncovered) which can be useful when using the expandable member102 for thrombectomy. Separately or additionally, the expandable member102 as a whole, or the distal portion 176, can be uncovered. Some or allof the portion of the outer surface of the expandable member 102 thatfaces radially outward, away from the central longitudinal axis of theexpandable member 102, can be uncovered such that theradially-outward-facing portion of the outer surface of the expandablemember 102 can comprise, in whole or in part, a vessel-wall-contacting,catheter-contacting, or thrombus-contacting surface. In someembodiments, such a vessel-wall-contacting catheter-contacting, orthrombus-contacting surface can be partially or entirely metallic,comprising metals of the galvanic cell, for example one or both of thefirst metal 180 and the second metal 182. In some embodiments, such avessel-wall-contacting, catheter-contacting, or thrombus-contactingsurface can be substantially or entirely free of one or more metals ofthe galvanic cell, for example one or both of cathodic metal (e.g., thefirst metal 180) or anodic metal (e.g., the second metal 182). In someembodiments, less than 50%, less than 40%, less than 25%, less than 10%,less than 5%, or less than 2% of a total surface area of the secondmetal can be at the vessel-wall-contacting, catheter-contacting, orthrombus-contacting surface. In some embodiments, less than 50%, lessthan 40%, less than 25%, less than 10%, less than 5%, or less than 2% ofa total surface area of the first metal can be at thevessel-wall-contacting, catheter-contacting, or thrombus-contactingsurface. It may be useful to provide an outward-facing surface or avessel-wall-contacting catheter-contacting, or thrombus-contactingsurface that is substantially or entirely free of anodic metal (i) tofacilitate delivery and retrieval by providing a lower displacementforce between the expandable member 102 (or a portion thereof) and acatheter, as compared to a force that would be required if the anoutward-facing surface or a vessel-wall-contacting catheter-contacting,or thrombus-contacting surface comprised anodic metal, (ii) to protectthe anodic metal from disruption, e.g., shearing, that might occur fromsliding contact between the anodic metal and the catheter, or both.

As discussed above, the expandable member 102 can comprise overlap zones128 in some embodiments. In some such embodiments, the outer surface ofthe expandable member in the overlap zones that would contact each otherin a volume-reduce form in a catheter or during transition between thevolume-reduced form and expanded configurations are substantially orentirely free of anodic metal. This may (i) facilitate delivery andretrieval by diminishing friction that may impede the expansion orcontraction of the expandable member (or a portion thereof), (ii) toprotect the anodic metal from disruption, e.g., shearing, that mightoccur from sliding contact between portions of the outer surface in theoverlap zones 128, or both

The ratio of anode surface area to cathode surface area affects thedensity of the generated current and the rate of the galvanic reaction.As the area of the anode becomes smaller compared to the cathode area,the current density increases and the reaction rate increases. Consider,for example, the filaments 178 shown in schematic cross-sections inFIGS. 19 and 20. As the galvanic cell of FIG. 19 has a higher ratio ofanodic to cathodic surface area, it would generate a lower chargedensity and have a slower corrosion rate in the galvanic cell of FIG.20. In a galvanic cell of the expandable member 102, the anodic metalcan form from about 35% or about 45% to about 75% or about 85% of atotal surface area of the galvanic cell. In the galvanic cells of someembodiments, the anodic metal can form about 35%, about 45%, about 55%,about 65%, about 75%, or about 85% of a total surface area of thegalvanic cell.

The thickness of the anode affects the total reaction time of thegalvanic cell. In some embodiments, the thickness of the anode isselected to provide 5-10, 15-20, or 20-25 minutes of reaction time. Infurther embodiments, the thickness of the anode can be selected toprovide 5-10 minutes of reaction time after positioning the expandablemember 102 in a blood vessel. In some embodiments wherein the anodecomprises magnesium and the cathode comprises nitinol, a magnesiumthickness of about 2 to 3 micrometers can provide at least about fiveminutes of reaction time, e.g. where the anode:cathode area ratio isabout 1:1. The thickness of the anodic metal may vary over a region ofits coverage. For example, when the anodic metal is applied to astructural material by vapor deposition, the anodic metal may bethicker, as measured in a direction normal to the receiving surface, inregions oriented directly toward the direction of deposition than otherregions.

Some or all of the expandable member 102 can be covered by a thin,dissolvable covering 188 (see FIGS. 16 and 18), e.g., film, that delayselectrical activity of the galvanic cell until an amount of time haspassed in the presence of a solvent, which may be a constituent ofblood. For example, a dissolvable covering can isolate the implant fromthe blood until it dissolves, allowing the user to position or otherwisemanipulate the expandable member before a galvanic reaction occurs. Thedissolvable covering can cover some or all of the mesh, the proximalportion 122, the distal portion 176, the contacting portion of the outersurface of the expandable member in the overlap zones, or a combinationthereof. The film can comprise a bioabsorbable polymer, for example,polylactic or polyglycolic acid, or a sugar, wax, oil, etc. Thedissolvable covering can have a low coefficient of friction of contactwith itself and a material forming an inner wall of a catheter, tofacilitate delivery and deployment of the expandable member.

Referring to FIGS. 21A-D, in some embodiments the expandable member 101can be used as a flow restoration device and/or an implantable member(e.g. stent) in a vessel, including at bifurcation, bi-vessel, and/ormulti-vessel locations in mammalian vasculature, e.g. in theneurovasculature or in the peripheral vasculature. For example, and withreference to FIG. 21A, thrombi can be located at bifurcations in theneurovasculature such as the internal carotid artery and the anteriorcerebral artery, or internal carotid artery and middle cerebral artery,or the basilar artery and the posterior cerebral artery. With referenceto FIG. 21B, thrombi can also be located at two vessels (i.e.bi-vessels) as two separate clots in similar vessels. With reference toFIGS. 21C and 21D, thrombi can also be located at multi-vessels as oneclot that is within multiple vessels or as multiple clots that arewithin multiple vessels. Vessels with such clots can be located, forexample, at the intracranial internal carotid, anterior cerebral andmiddle cerebral arteries, and basilar artery and both posterior andcerebral arteries, or in the peripheral vasculature, such as the deepvenous system of the legs when treating deep vein thrombosis.

Referring to FIG. 22, the medical device 100 can be used in a systemwith a balloon guide catheter 164, with a syringe 166 for expanding aballoon 168, a syringe 170 for aspiration, or both. Aspirationassistance can enable flow reversal through the expandable member 102and thrombus 162. Inflation of the balloon 168 can impede or preventflow proximally through the vessel from the balloon 168 towards theexpandable member 102. As part of the retrieval procedure, continuousaspiration can be employed through the balloon guide catheter 164, withvigorous aspiration when the expandable member 102 is near a distal tipof the balloon guide catheter. The aspiration with flow reversal canhelp allow the distal vasculature to continue to have blood perfusingthrough the vessels during the retrieval process, and can inhibit thepossibility of distal emboli. There can be an advantage to having bloodflow across the expandable member 102 and thrombus 162 with thepotential of natural lysing of blood and increased surface area forthrombus dissolving medicines, if they are provided. The aspiration withflow reversal can also assist in the thrombus retrieval process byaiding in the removal of the thrombus 162. The flow can be directedtowards a lumen of the balloon guide catheter 164 due to the aspiration.The expandable member 102 and thrombus 162 can thus be assisted by theflow to enter the lumen of the balloon guide catheter 164. In someembodiments, if withdrawal into the balloon guide catheter 164 isdifficult for any reason during aspiration, the balloon 168 can bedeflated, and the balloon guide catheter 164, catheter 107, andexpandable member 102 can be withdrawn simultaneously while maintainingaspiration.

A technique for engaging and removing a thrombus 162 and restrictingdownstream travel of secondary emboli during thrombus retrieval will nowbe discussed with reference to FIGS. 23-32. This technique can beperformed with any of the embodiments of the medical device 100 andexpandable member 102 disclosed herein, including any of the expandablemembers 102 of FIG. 2, 8, 9 or 10. Referring to FIG. 23, the medicaldevice 100 may be inserted into an anatomical vessel 172 by firstinserting a guide wire 174 into the anatomical vessel 172. The guidewire 174 is advanced through a guide catheter 164, which optionallyincludes a balloon near the guide catheter's distal end, and a catheter107 to the treatment site, adjacent the thrombus 162. Referring to FIG.24, the guide wire 174 is advanced distally through the thrombus 162.Once in position, the catheter 107 is advanced over the guide wire 174,through a distal end of the guide catheter, into the anatomical vessel172. Referring to FIG. 25, the catheter 107 is advanced distally throughthe thrombus 162. The guide wire 174 is then withdrawn proximally.

Referring to FIG. 26, the medical device 100 is advanced through thecatheter 107 such that the distal portion 120 of the medical device 100is disposed distal of the thrombus 162 in the anatomical vessel 172. Themedical device 100 is advanced through the catheter 107 by themanipulation member 104 coupled to the proximal end of the expandablemember 102. The catheter 107 compresses the expandable member 102 andthus, maintains the expandable member 102 in a compressed,volume-reduced configuration as the expandable member 102 is advanced tothe treatment site.

Referring to FIGS. 27 and 28, the catheter 107 is withdrawn proximallyrelative to the expandable member 102 to expose the expandable member102. If the expandable member is self-expanding, retraction of thecatheter 107 can permit the expandable member 102 to expand. The frame108 expands against a length of the thrombus 162 and engages thethrombus 162. As discussed above, the frame 108 is designed to engageand remove thrombi that are both generally soft, or malleable, orgenerally hard, or callous. A period of time can be allowed to pass toallow blood to reperfuse the downstream area, the expandable member 102to penetrate the thrombus 162, or both.

Once the expandable member 102 has been expanded into the thrombus 162,the expandable member 102 can grip the thrombus, by virtue of itsability to mechanically interlock with the thrombus as well as itsability to electrically attract, adhere, and/or attach to the thrombus162. The galvanic cell(s) and/or region(s) can begin a galvanic reactionbefore or after the expandable member 102 has been released from thecatheter 107 into the anatomical vessel 172 (e.g., an intracranialvessel) and/or expanded into the thrombus 162. The expandable member 102can be left in place or manipulated within the vessel for a time periodwhile the galvanic cell(s) and/or region(s) are reacting. Any positivelycharged portions of the expandable member 102 can attract negativelycharged constituents of the thrombus 162, and any negatively chargedportions of the expandable member 102 can attract positively chargedconstituents of the thrombus 162, thereby enhancing the grip of theexpandable member 102 on the thrombus 162. This allows the expandablemember 102 to be used to retrieve the thrombus 162 (discussed below)with reduced risk of losing grip on the thrombus or a piece thereof,which can migrate downstream and cause additional vessel blockages inareas of the brain that are more difficult to reach. These advantagescan be achieved via the galvanic cell(s) and/or region(s) discussedherein, without need for a separate, extracorporeal voltage source,wires, or other conductors extending from the source to the expandablemember 102, or switches or other controls regulating the application ofvoltage.

In some embodiments, at least a portion of the thrombus 162 isattracted, adhered, and/or attached to an inwardly facing surface of theexpandable member 102. Blood constituents can be bound primarily orsubstantially only to an inwardly facing surface of the mesh in someembodiments.

With reference to FIGS. 29-31, once the endovascular expandable member102 has engaged and captured the thrombus 162, the thrombus 162 can beremoved. For example, the expandable member 102 with the thrombus 162gripped thereby, can be retracted (for example, along with themicrocatheter 108) proximally toward the balloon guide catheter. Duringthis retraction, the expandable member 102 can grip the thrombus 162electrostatically, e.g., via the galvanic cell(s) and/or region(s)discussed herein. Accordingly, the expandable member 102 can maintain anenhanced or electrostatically-enhanced grip on the thrombus 162 duringretraction. The expandable member 102 and thrombus therefore form aremovable, integrated thrombus-device mass wherein the connection of thethrombus to the device is electrostatically enhanced, e.g. via thegalvanic cell(s) and/or region(s) discussed herein.

Prior to retracting the expandable member 102 and thrombus 162, thecatheter 107 or the guide catheter 164 can be manipulated. For example,the catheter 107 or the guide catheter 164 can be moved forward to apredetermined point relative to the expandable member 102. Use ofmarkers along the catheter 107, or the guide catheter 164, and/orexpandable member 102 can be used to determine the relative locations ofthe catheter 107, the guide catheter 164, and expandable member 102.Description of the use of such markers can be found, for example, in PCTPublication No. WO 2009/105710, which is incorporated by reference inits entirety.

Referring to FIGS. 29 and 30, the expandable member 102 is withdrawnproximally, along with the thrombus 162. Applying a proximally directedforce to a proximal end of the frame 108 can collapse a distal end ofthe frame 108, prior to withdrawal of the intervention member into theguide catheter 164. The distal end of the frame 108 can collapse to atleast substantially the same extent, and optionally more than, a portionof the frame proximal of the distal end as discussed above.

Referring to FIGS. 22, 30, and 31, in embodiments wherein the guidecatheter 164 comprises a balloon 168, the balloon optionally can beinflated to occlude flow during retraction of the thrombus 162 towardthe guide catheter. In some embodiments, an aspiration syringe 170 canbe attached to the guide catheter 164, and aspiration can be applied toaid thrombus retrieval.

Referring to FIG. 31, the expandable member 102 is withdrawn proximallyto the guide catheter 164. The guide catheter 164 causes the frame 108to collapse, with the thrombus 162 engaged therein. The thrombus 162 isthus retrieved and removed from the anatomical vessel 172. Referring toFIG. 32, if retrieval of the expandable member 102 is determined to beundesirable, e.g., to avoid damaging the vessel 172, and the expandablemember 102 is detachably connected to the manipulation member 104, theexpandable member can be detached from the manipulation member 104 andcan remain in the vessel 172.

Additionally, while the expandable member 102 described above has beendescribed in the context of use during a blood flow restorationprocedure, the expandable member 102 can also, or alternatively, be usedas an implantable member (e.g. stent). For example, the expandablemember 102 can be released through the connection 106 at a stenosis,aneurysm, or other appropriate location in a vessel. The expandablemember 102 can expand and engage a vessel wall so as to hold the vesselwall open and/or act as an occluding member. While the filamentthicknesses, widths, cell sizes, and forces described above can beoptimized for an expandable member 102 for flow restoration, thesevalues can also be optimized for an expandable member 102 for use as animplantable member. In some embodiments the same values can be used forboth flow restoration and use as an implantable member.

Further details regarding expandable members, the manufacture ofexpandable members, and use of expandable members are disclosed in U.S.Pat. No. 7,300,458, entitled Medical Implant Having a Curable MatrixStructure, issued Nov. 27, 2007; U.S. Patent Application Publication No.2011/0060212, entitled Methods and Apparatus for Flow Restoration,published on Mar. 10, 2011; U.S. Patent Application Publication No.2012/0083868, entitled Methods and Apparatuses for Flow Restoration andImplanting Members in the Human Body, published on Apr. 5, 2012; U.S.Patent Application Publication No. 2011/0160763, entitled Blood FlowRestoration in Thrombus Management Methods, published on Jun. 30, 2011;U.S. Patent Publication No. 2014/0194919, entitled Connection of anEndovascular Intervention Device to a Manipulation Member, published onJul. 10, 2014; and U.S. Patent Publication No. 2014/0194911, entitledConnection of a Manipulation Member, Including a Bend withoutSubstantial Surface Cracks, to an Endovascular Intervention Device,published on Jul. 20, 2014; and U.S. patent application Ser. No.14/026,302, entitled Endovascular Device Engagement, filed on Sep. 13,2013; the entirety of each of which is hereby incorporated by referenceherein.

The foregoing description is provided to enable a person skilled in theart to practice the various configurations described herein. While thesubject technology has been particularly described with reference to thevarious figures and configurations, it should be understood that theseare for illustration purposes only and should not be taken as limitingthe scope of the subject technology.

There may be many other ways to implement the subject technology.Various functions and elements described herein may be partitioneddifferently from those shown without departing from the scope of thesubject technology. Various modifications to these configurations willbe readily apparent to those skilled in the art, and generic principlesdefined herein may be applied to other configurations. Thus, manychanges and modifications may be made to the subject technology, by onehaving ordinary skill in the art, without departing from the scope ofthe subject technology.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an illustration of exemplary approaches. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged. Some of the stepsmay be performed simultaneously. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

As used herein, the phrase “at least one of” preceding a series ofitems, with the term “and” or “or” to separate any of the items,modifies the list as a whole, rather than each member of the list (i.e.,each item). The phrase “at least one of” does not require selection ofat least one of each item listed; rather, the phrase allows a meaningthat includes at least one of any one of the items, and/or at least oneof any combination of the items, and/or at least one of each of theitems. By way of example, the phrases “at least one of A, B, and C” or“at least one of A, B, or C” each refer to only A, only B, or only C;any combination of A, B, and C; and/or at least one of each of A, B, andC.

A phrase such as “an aspect” does not imply that such aspect isessential to the subject technology or that such aspect applies to allconfigurations of the subject technology. A disclosure relating to anaspect may apply to all configurations, or one or more configurations.An aspect may provide one or more examples of the disclosure. A phrasesuch as “an aspect” may refer to one or more aspects and vice versa. Aphrase such as “an embodiment” does not imply that such embodiment isessential to the subject technology or that such embodiment applies toall configurations of the subject technology. A disclosure relating toan embodiment may apply to all embodiments, or one or more embodiments.An embodiment may provide one or more examples of the disclosure. Aphrase such “an embodiment” may refer to one or more embodiments andvice versa. A phrase such as “a configuration” does not imply that suchconfiguration is essential to the subject technology or that suchconfiguration applies to all configurations of the subject technology. Adisclosure relating to a configuration may apply to all configurations,or one or more configurations. A configuration may provide one or moreexamples of the disclosure. A phrase such as “a configuration” may referto one or more configurations and vice versa.

Terms such as “top,” “bottom,” “front,” “rear” and the like as used inthis disclosure should be understood as referring to an arbitrary frameof reference, rather than to the ordinary gravitational frame ofreference. Thus, a top surface, a bottom surface, a front surface, and arear surface may extend upwardly, downwardly, diagonally, orhorizontally in a gravitational frame of reference.

Furthermore, to the extent that the term “include,” “have,” or the likeis used in the description or the claims, such term is intended to beinclusive in a manner similar to the term “comprise” as “comprise” isinterpreted when employed as a transitional word in a claim.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments.

A reference to an element in the singular is not intended to mean “oneand only one” unless specifically stated, but rather “one or more.”Pronouns in the masculine (e.g., his) include the feminine and neutergender (e.g., her and its) and vice versa. The term “some” refers to oneor more. Underlined and/or italicized headings and subheadings are usedfor convenience only, do not limit the subject technology, and are notreferred to in connection with the interpretation of the description ofthe subject technology. All structural and functional equivalents to theelements of the various configurations described throughout thisdisclosure that are known or later come to be known to those of ordinaryskill in the art are expressly incorporated herein by reference andintended to be encompassed by the subject technology. Moreover, nothingdisclosed herein is intended to be dedicated to the public regardless ofwhether such disclosure is explicitly recited in the above description.

While certain aspects and embodiments of the subject technology havebeen described, these have been presented by way of example only, andare not intended to limit the scope of the subject technology. Indeed,the novel methods and systems described herein may be embodied in avariety of other forms without departing from the spirit thereof. Theaccompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of thesubject technology.

1. (canceled)
 2. A method for performing an endovascular therapy,comprising: identifying a blood vessel in which blood flow is impeded bythrombus; inserting a medical device into the blood vessel, the medicaldevice comprising: an elongate manipulation member comprising a distalend portion; and an intervention member comprising a proximal endportion and a mesh, the proximal end portion being coupled with thedistal end portion of the elongate manipulation member, the mesh havinga plurality of cells in a tubular configuration and being compressibleto a collapsed configuration for delivery to an endovascular treatmentsite through a catheter and being self-expandable from the collapsedconfiguration to an expanded configuration; expanding the mesh into atleast a portion of the thrombus; generating an electrical charge on atleast a portion of the mesh, thereby electrically assisting attachmentof at least a portion of the thrombus to the mesh; and removing themedical device from the blood vessel with at least the attached portionof the thrombus.
 3. The method of claim 2, wherein generating theelectrical charge occurs while the intervention member is within theblood vessel.
 4. The method of claim 3, wherein generating theelectrical charge occurs while the mesh is engaged with the thrombus. 5.The method of claim 2, further comprising aspirating the blood vessel atthe endovascular treatment site while generating the electrical chargeto facilitate removal of the thrombus.
 6. The method of claim 2, whereinelectrically assisting attachment of at least a portion of the thrombuscomprises binding, through electrical attraction, blood constituents toa positively charged region of the mesh.
 7. The method of claim 6,wherein the blood constituents are bound primarily to an inwardly facingsurface of the mesh.
 8. The method of claim 2, wherein the blood vesselcomprises an intracranial blood vessel.
 9. The method of claim 2,wherein inserting the medical device comprises inserting it to alocation laterally adjacent to at least a portion of the thrombus. 10.The method of claim 2, wherein generating the electrical charge occursfor between 5-25 minutes.
 11. A method for performing an endovasculartherapy, comprising: inserting a medical device into a blood vesselhaving a thrombus therein, the medical device comprising: an elongatemanipulation member comprising a distal end portion; and an interventionmember comprising a proximal end portion coupled with the distal endportion of the elongate manipulation member, the intervention memberbeing compressible to a collapsed configuration for delivery to anendovascular treatment site through a catheter and being self-expandablefrom the collapsed configuration to an expanded configuration; expandingthe intervention member into at least a portion of the thrombus;generating a positively electrically charged region of the interventionmember, thereby electrically assisting attachment of at least a portionof the thrombus to the intervention member; and removing the medicaldevice from the blood vessel with at least the attached portion of thethrombus.
 12. The method of claim 11, wherein generating the electricalcharge occurs while the intervention member is within the blood vessel.13. The method of claim 12, wherein generating the electrical chargeoccurs while the intervention member is engaged with the thrombus. 14.The method of claim 11, further comprising aspirating the blood vesselat the endovascular treatment site while generating the electricalcharge to facilitate removal of the thrombus.
 15. The method of claim11, wherein electrically assisting attachment of at least a portion ofthe thrombus comprises binding, through electrical attraction, bloodconstituents to a positively charged region of the intervention member.16. The method of claim 15, wherein the blood constituents are boundprimarily to an inwardly facing surface of the intervention member. 17.The method of claim 11, wherein the blood vessel comprises anintracranial blood vessel.
 18. The method of claim 11, wherein insertingthe medical device comprises inserting it to a location laterallyadjacent to at least a portion of the thrombus.
 19. The method of claim11, wherein generating the electrical charge occurs for between 5-25minutes.
 20. The method of claim 11, wherein the intervention member istubular.
 21. The method of claim 11, wherein the intervention membercomprises a mesh having a plurality of cells.